This invention relates to a pumping system useful in dispensing fluids, especially those that are expensive, viscous, high purity, and/or sensitive to molecular shear. The invention also relates to microelectronic components such as silicon chips and wafers, microelectronic substrates, and circuits fabricated by such pumping systems and methods, including the potentially improved quality and yield of such products achievable with the invention as compared to prior art systems.
General aspects of the relevant background of the invention are discussed in prior U.S. Pat. Nos. 5,167,837; 5,772,899; and 5,516,429. Among other things, the invention has numerous applications, but is especially useful in the microelectronics industry. The trend in that industry continues to be to squeeze greater quantities of circuitry onto smaller substrates. Circuit geometries continue to shrink, the use of expensive materials continues, and the corresponding need for decontaminated xe2x80x9ccleanroomxe2x80x9d environments and equipment for manufacturing, filtering, and processing continues and even increases. Perhaps as importantly, the need for improved yield of final product continues, for economic and other reasons.
The equipment and methods of the aforementioned U.S. Pat. Nos. 5,167,837; 5,772,899; and 5,516,429 addresses many situations and applications very well. The present invention is directed to further improvements in that technology, as well as potential applications of such improvements in unrelated technologies.
Among other things, further simplification and upright orientation of the flow path for the processed fluids through a pumping and dispensing system can reduce the risk of contamination, air entrapment, or similar concerns, while providing similar or improved reliability and precise control for desired filtration, dispense, and other handling of the process fluids. Further manufacturing and design improvements in the instant invention allow the entire process fluid flow path to be coated or machined from Teflon(copyright) or some similar non-contaminating material, further reducing the likelihood of any contamination problems.
As indicated above, many problems were addressed and solved by the aforementioned U.S. Pat. Nos. 5,167,837, 5,516,429, and 5,772,899. Among other things, those devices introduced a diaphragm-type fluid dispense system which, in certain embodiments, included two separate computer-controlled pumps to dispense precise amounts of fluid. However, the preferred embodiments in those patents show the process fluid traveling in a somewhat meandering path through the pump system. In certain applications, that path does not afford optimal venting for any contaminating air bubbles that may become entrapped in the fluid or the system. For example, some small amount of air bubbles may be unavoidably introduced when the source fluid container is periodically changed, even if no re-priming is required. Portions of the flow path that are metal or otherwise relatively potentially contaminating result in some risk (however small) of corresponding undesirable contamination of the fluid.
As indicated in those prior patents, such bubbles or contaminants could potentially compromise the end product to some degree in some small percentage of applications. Alternatively, such bubbles or contaminants might require some period of xe2x80x9cflushingxe2x80x9d bubbles from the system upon changing the source fluid container, for example, or might otherwise compromise the accuracy of the fluid dispense system (again, in a small percentage of applications and situations). Although those prior patents and inventions function well in that regard and are a dramatic advance over the prior art before them, and although those prior patents can be readily adapted to deal with the aforementioned potential problems, the instant invention provides improvements in that regard.
Other benefits derive from simplifying the flow path of the fluid. By simplifying and reducing the number of components involved in the system, assembly and maintenance can be correspondingly simplified. Perhaps more importantly, the number of connection points, seals, fittings, and related potential leak-spots can be reduced, thereby directly reducing the risk of contamination, air-entrainment, or similar problems. Additionally, reducing and realigning the fluid flow path can reduce the size of the xe2x80x9cfoot-printxe2x80x9d for the housing of the system and otherwise make the system more compact as compared to prior art systems, thereby correspondingly reducing valuable factory space for the users of the pump system.
It is, therefore, an object of my invention to provide a fluid dispensing system that provides the improved performance and benefits discussed herein. The system is characterized by substantially vertical fluid flow from its inlet to its outlet when the system is in its normally upright position, and by providing Teflon(copyright) or similar non-contaminating wetted surfaces throughout the flowpath. In its preferred embodiment, the flow path is simplified as compared to prior art systems, including fewer fittings and connections (in part resulting from integrally forming various components into single unitary structures).
A further object of the invention is the provision of a device for processing fluid in a precisely controlled manner, including the combination of first pumping means and second pumping means in fluid communication with each other, in which the fluid travel path that is substantially consistently upward as the fluid flows through the first pumping means and the second pumping means. As indicated above, the first and second pumping means surfaces that contact the fluid are preferably all fabricated from or coated with a relatively non-contaminating material, such as Teflon(copyright) or the like. Among other things, this facilitates using the system for high-purity fluids, in cleanroom environments, etc.
The device can further include filter means between the first pumping means and the second pumping means, in which case the fluid travel path preferably remains substantially consistently upward as the fluid flows through the first pumping means, the filter means, and the second pumping means, and all or substantially all contacting surfaces are non-contaminating. In the preferred embodiment, the pump head and the valve therein are actually fabricated from Teflon(copyright), and all fittings along the flow path are flare fittings formed from Teflon(copyright) or otherwise having wetted surfaces that are non-contaminating to the subject fluid. For the non-contaminating aspect of the invention, the particular material may be any suitable non-contaminating material, including without limitation various forms of Teflon(copyright) (TFE and PFA), Kalrez (a fluorinated, Teflon(copyright)-like elastomer), or other materials. Among the many suitable fittings usable in the invention, commercially available Furon Flare Grip(copyright) PFA tube fittings can be readily utilized.
Another object of the invention is the provision of a system or device of the aforementioned character, in which the first pumping means includes an upper head portion removable from a lower portion, and means are provided for temporarily attaching the upper head portion to a lower portion to form a pumping chamber therebetween. Preferably, the upper head portion includes integrally formed valve means configured to thereafter direct the process fluid in a substantially upward path toward a filter chamber integrally formed in the upper head portion. Among other things, the integral valve facilitates filtering viscous and other fluids under relatively low pressure, and decreases molecular shear on the fluids, in part by providing relatively larger and less obstructed flow paths through the valve (as compared to prior art systems). The valve also reduces differential pressure, or pressure drop, as the fluids move through the valve.
An additional object of the invention is the provision of a system or device of the aforementioned character, in which the second pumping means includes an upper head portion removable from a lower portion, with means for temporarily attaching the upper head portion to the lower portion to form a pumping chamber therebetween. Again preferably, the upper head portion of the second pumping means includes an integrally formed tee fluid flowpath therein, wherein the tee provides a substantially direct upward flowpath for the subject fluid from the pumping chamber toward a dispense from the upper head portion. The preferred tee includes an input portion for receiving the subject fluid after it has been pumped by the first pumping means, and the dispense from the second pump""s upper head portion is positioned higher than the input portion when the device is in its normal, upright orientation.
A further object of the invention is the provision of a system or device of the aforementioned character, in which the second pumping means is positioned generally above the first pumping means, and the fluid travel path from an exit of the first pumping means to an inlet into the second pumping means does not include any downwardly directed portions when the device is in its normal, upright orientation.
A still further object of the invention is the provision of a device for dispensing fluid, including the combination of a first diaphragm-type pump having a pumping head, the head including an integrally formed valve to control flow of fluid into the first diaphragm-type pump. The device can further include a second diaphragm-type pump positioned generally above the first diaphragm-type pump and configured to receive fluid pumped by the first diaphragm-type pump, and having a fluid path from the first diaphragm-type pump to the second diaphragm-type pump that is generally upward.
Yet another object of the invention is the inclusion of a vent valve above or upstream of the filter to permit selective venting of any gas entrained in the subject fluid. Preferably, the vent valve can also function as a pressure relief or safety valve, to prevent the pressure on the subject fluid and the system itself from exceeding a selected level. Also preferably, the vent valve is positioned at a high point within the filter chamber.
Other objects of the invention are directed to a method for filtering and dispensing fluid, including one or more of the steps of providing a valve means integrally formed in an upper head of a first pumping member, the valve means configured to receive the subject fluid and direct it in a substantially upward path from the first pumping member; actuating the first pumping member to draw the subject fluid from a source; and further actuating the first pumping member to dispense the subject fluid upwardly from the first pumping member. In the preferred embodiment, the valve switches the fluid flow drawing and dispensing steps in the preceding sentence. As indicated above, the steps can further include providing a filter chamber integrally formed in the upper head of the first pumping member and providing a substantially direct upward flow path within the upper head from the first pumping member through the valve means to the filter chamber, whereby further actuation of the first pumping member directs the subject fluid upwardly from the first pumping member to the filter chamber.
Additional steps of the methods of the invention include providing a second pumping member substantially above the first pumping member and providing fluid flow means therebetween, whereby the subject fluid does not flow downwardly between the first pumping member and the second pumping member; and pumping the subject fluid along the non-downward flowpath.
Another object of the invention is the provision of apparatus and methods that include providing a valve downstream of the second pumping member for selectively dispensing the subject fluid or returning the subject fluid to the source, in which the downstream valve is a substantially zero displacement valve that does not undesirably contaminate or introduce gas into the subject fluid. Among other things, the preferred valve reduces or eliminates the likelihood that operating the valve will displace fluid (such as displacing it from the dispense line), which displacement could adversely affect the accuracy of dispense or other aspects or performance of the system.
Although the invention is described herein in connection with dispense of high-purity, viscous fluids, the invention may be utilized in many other applications.
Moreover, although the preferred embodiment discussed herein includes two pumping means with filter means interposed therebetween, advantageous aspects of the invention may be practiced with no filter means, or with only one pumping means with or without filter means.
As with prior art systems, my invention provides a dispensing system permitting the use of computer or other automated digital control for the rate and interval of dispense, as well as for the direction of fluid flow through the system and fluid pressure during operation of the system. Thus, still another object of my invention is the provision of a dispensing system that permits great flexibility of operation, making it adaptable to numerous applications. The system may be controlled or driven by stepper or servomotors, or similar technology, and by various computer software, hardware, and wiring or wireless communication systems.
Other objects of my invention include providing a relatively shorter fluid flow path such that contaminants are less likely to be introduced, and a relatively more compact pump design that leaves a smaller xe2x80x9cfootprintxe2x80x9d (as compared to prior art devices).
An additional object of the invention is the provision of integrated circuits, chips, or other microelectronic devices fabricated from the aforementioned apparatus or methods.
Other objects and advantages of the invention will be apparent from the following specification and the accompanying drawings, which are for the purpose of illustration only.